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a(n) = smallest base-4 palindrome m >= n such that every base-4 digit of n is <= the corresponding digit of m; m is written in base 4.
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%I #4 Dec 10 2015 10:36:45

%S 0,1,2,3,11,11,22,33,22,22,22,33,33,33,33,33,101,101,202,303,111,111,

%T 212,313,121,121,222,323,131,131,232,333,202,202,202,303,212,212,212,

%U 313,222,222,222,323,232,232,232,333,303,303,303,303,313,313,313,313,323,323,323,323,333,333,333,333,1001,1001,2002,3003,1111,1111,2112,3113,1221,1221,2222,3223,1331,1331,2332,3333

%N a(n) = smallest base-4 palindrome m >= n such that every base-4 digit of n is <= the corresponding digit of m; m is written in base 4.

%Y Sequences related to palindromic floor and ceiling: A175298, A206913, A206914, A261423, A262038, and the large block of consecutive sequences beginning at A265509.

%K nonn,base

%O 0,3

%A _N. J. A. Sloane_, Dec 10 2015